In internal combustion engines, pistons are housed within corresponding cylinders for reciprocating movement therein. Fuel and air enter a combustion chamber in a cylinder on a first side of a piston. The fuel in the combustion chamber is ignited to cause linear motion of the piston inside the respective cylinder. The linear motion of the piston is then converted to rotary motion by the crankshaft.
Ideally, all of the gases in the combustion chamber(s) after ignition of the fuel would be exhausted via an engine exhaust pipe. However, a portion of the combustion gases typically passes between the piston rings and the cylinder walls of the cylinders housing the pistons. The combustion gases typically are routed through the crankcase and into the air intake system of the engine so as to prevent pressurizing the crankcase. During such routing of the combustion gases, the gases often become contaminated with oil mist as the high pressure gases are blown past the piston rings into the crankcase. The mixture of combustion gases and oil mist is known as crankcase blow-by, or simply blow-by.
A breather apparatus can be attached to, or incorporated into, an internal combustion engine so that the oil content in the blow-by gas is separated out. The oil can then be returned to inner components of the engine, such as an oil pan. Breathers typically fall into two classifications: external canister-type breathers that can be attached to the engine, and internal-type breathers that are integral to (or otherwise formed as part of) the engine crankcase. An external canister-type breather is typically attached to the crankcase and induction system via hoses. This utilizes multiple assembly joints that require assembly time and create a potential for oil leakage. Additionally, the canister is placed on the outside of the engine and takes up much desired space. Further, the path from the crankcase through the canister is not readily accessible.
In contrast, an internal breather is typically formed into the crankcase. While not requiring numerous hoses, or occupying large amounts of space outside the engine, an internal breather typically adds cost to both the casting tool and the casting piece price, as the casting is more complex. Moreover, there are additional costs to machine the casting itself.
For at least these reasons, therefore, an improved internal breather device for separating oil from blow-by in an internal combustion engine is desired.